From: Bert Hickman
Date: Wed, 29 May 2002 07:46:38 -0500
Subject: Re: Top V Probe Design (was RE: [TSSP] Topload breakout potentials)
Hi Malcolm,
This could work in principle, but I think a larger amount of capacitance
would be desirable in practice to reduce AC ratio errors introduced by
the stray capacitance between voltage grading toroids/rings and to the
surrounding secondary winding. I'd think that we'd want to keep the
capacitance between successive stages at least 100X as large as the
parasitic capacitance to reduce the effects of capacitive coupling from
the surrounding secondary.
I've begun a design spreadsheet that should help do "what if" designs
for a modular (staged) divider. The proposed configuration would have a
series of identical modules (stages), each of which can "plug" into the
stage above or below for easy stacking. Each module (or stage) would
consist of identical chains of R's and C's that physically fit well
inside the cylinder between grading rings. Input parameters would
include the desired voltage capability per stage, resistor element value
(Re) and number of resistors in series/stage (M), capacitor element
value (Ce) and number of capacitors in series/stage (N), total number of
stages, and desired overall divider ratio. The number of resistors/stage
(M) can differ from the number of caps/stage (N) to provide maximum
design flexibility.
The base resistor and cap would have the same RC value, but would be
sized to provide a total 1000:1 voltage ratio across the entire divider.
Corona management and E-field control will be the key....
-------------
( ) ROC sufficient to prevent corona
-------------
| M Re elements/stage
o---///--///--......--///--///--
| Re |
| |
| | | | | | | | | |
o----| |------| |--.......----| |-----| |---o
| | | | | | | | |
Ce N Ce elements/stage |
|
--------------------------------------------
|
-------------
( )
-------------
.
. 10 identical stages
.
| Rbase Cal Adj
|
o-------////--o--////----
| | ^ |
| |------| |
| | | |
o----------| |-------------------o
| | | |
| Cbase |
Out ------
/ / /
Will discuss more later - got to go to work now...
Best regards,
-- Bert --
--
Bert Hickman
Stoneridge Engineering
Coins Shrunk Electromagnetically!
http://www.teslamania.com
Malcolm Watts wrote:
>
> Hi Bert, all,
> It occurred to me last night that if the central
> divider chain were to be a compensated RC ladder, it might be
> possible to make a resistive chain self-compensating by using the
> stray capacitance between resistors. Essentially, by arranging the
> resistors in the following fashion:
>
> |
> ---///--
> |
> ---///--
> |
> ---///--
> |
> ---///--
> |
>
> etc. and suitably sizing the resistors such that their resistance
> matched the parasitic capacitive reactance, we might obtain such a
> result.
>
> ?
>
> Regards,
> Malcolm
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.